Roll presses are machines for the size reduction of material beds with usually two rollers, which are also called rolls and are arranged in a machine frame. To reduce the size of beds of material, the particles are drawn into a roll gap, pressed against one another by the high pressure exerted by the rolls and they mutually reduce each other's size. One of the rolls is usually designed as a fixed roll and one as a movable roll. Roll presses are also called cylinder crushers or roller presses and are used in cement production as well as in mining.
The machine frame must absorb the strong radial forces and, moreover, the occurring axial forces. A twisting of the machine frame is to be avoided, because such leads to incorrect positioning of the rolls and hence to an inhomogeneous pressure distribution accompanied by a deterioration of the result of size reduction. The rolls are guided with their bearings in the machine frame and are held in position in the axial direction, and an oblique position and the possibility of a horizontal motion of the rolls and the bearing thereof in the frame are at the same time made possible. The movable roll has a markedly greater freedom of motion than the fixed roll due to being supported by hydraulic cylinders.
It is regularly necessary for maintenance and repairs to remove the rolls from the machine frame. End pieces that can be quickly removed, by means of which the frame can be opened on one side and the rolls can be removed in the horizontal direction, are frequently provided for this on at least one side of the frame.
DE 10 2005 061 085 A1 describes a roll press, which has a cuboid, closed frame, comprising an upper chord and a lower chord. The radial forces are absorbed by the chords as pulling forces. The axial forces are introduced into supports, which are fastened laterally to the chords and axially define the rolls. The chords are also loaded now with a component of the weight of the rolls. The drawback of this machine frame for a roll press is the heavy weight and the great effort needed for disassembly for repair purposes.
DE 10 2005 045 273 A1 shows a roll press, having a machine frame comprising a plurality of welded elements, which are connected to one another by a shearing pin screw connection. The mounted rolls, one being a movable roll with hydraulic support and the other being a fixed roll, are guided slidingly with low friction in the frame. The closed frame absorbs the pressing forces in the radial and axial directions and therefore has a correspondingly rigid design. The frame can be opened easily and rapidly on the fixed roll side, so that the mounted rolls can be rapidly removed and installed in the horizontal direction. The drawback is that the manufacture of this frame requires a large amount of material and is therefore cost-intensive. The repair of the frame is expensive as well.
DE 10 2010 015 374 A1 also shows a machine frame for a roll press. The frame is likewise of a cuboid design, but the screw and pin connections were replaced by welded connections by means of a U-shaped connection piece having two legs (tuning fork shape). This frame has a markedly lower weight than the above-described one, but it can absorb the occurring axial forces to a limited extent only because of the “open” frame design on one side, which is dictated by the function, and it would therefore disadvantageously twist during operation.